Slice a little off bottom of each potato so it can stand without rolling. Slice a little off top, then hollow out a small cavity using a sharp paring knife or melon baller. Place potato trimmings in a small saucepan, cover with water and season with salt. Oil insides and outsides of hollowed potatoes, generously season with salt and pepper, place on a baking sheet and bake until tender and golden, about 20 minutes.